Northwest Africa 16252 (NWA 16252)
Mali
Purchased: 2023 Feb
Classification: Ureilite
History: Found in Mali and purchased by Mbark Arjdal from a Malian dealer in February 2023.
Petrography: (A. Irving, UWS, and P. Carpenter, WUSL) Protogranular aggregate (mean grainsize ~1 mm) composed predominantly of olivine and low-Ca pyroxene with accessory pigeonite, kamacite, Cr-troilite, troilite and graphite plus minor secondary barite and celestite. Olivine grains have more magnesian reduced rims containing blebby Fe metal partially altered to Fe oxides.
Geochemistry: Olivine (cores Fa23.0-23.3; 14.5; Cr2O3 0.45-0.55 wt.%, CaO 0.20-0.31 wt.%; N = 3; rims Fa0.9-1.6, N = 3), low-Ca pyroxene (Fs2.6-19.2WWo4.6-5.1, Al2O3 0.7-1.8 wt.%, Cr2O3 0.6-1.2 wt.%, TiO2 0.1±0.0 wt.%, N = 4), pigeonite (Fs19.4Wo10.8, Al2O3 1.6 wt.%, Cr2O3-1.2 wt.%, TiO2 0.1 wt.%).
Classification: Ureilite.
Specimens: 24.6 g including one polished thin section at UWB; remainder with Mr. M. Arjdal.